Hybrid method for both calibration and registration of an endoscope with an active optical tracker

In this paper, we present a hybrid method for calibration of an endoscope and its registration with an active optical tracker. Practically, both operations are done simultaneously by moving an active optical marker in the field of view of the two devices. By segmenting image data, the LEDs composing the marker are extracted and the transformation matrix between the two referentials (homography) is calculated. By reformulating the calibration problem, registration and calibration parameters are extracted from the homography. As camera calibration and registration is an indispensable step for augmented reality or image guided applications, this technique can easily be used in the operating field because it is fast, accurate and reliable. We currently are using this technique with an augmented reality system for laparoscopic procedures.